MAMEWorld Forums - Ultimarc - ArcadeVGA 5000 vs. GBS-8100 scan rate converter

I recently purchased a GBS 8100 scan rate converter for a rebuild of my Mame cabinet. My initial reason for doing so, is that the ATI drivers (in general, this isn't a slam on the ArcadeVGA in particular) are ... well, let's just say that they aren't nearly as compatible with emulators as anything from NVidia. Also, I wasn't able to find any reviews anywhere on the net by anyone who has really tested this with an eye towards how well the scan rate converter deals with smooth scrolling games.

I purchased an ArcadeVGA 5000 (PCI-express to upgrade from the old AGP ArcadeVGA card in the machine) as well as a Geforce 640 + GBS 8100 converter.

Testing:
Testing was performed with 3 monitors: An Acer AL1917 flat panel LCD (vga input, semi-modern, doesn't accept anything below 31khz), a Commodore 1084 monitor with composite input from the GBS-8110 (standard resolution circa 1988), and a "Loop" brand monitor which is a rebadged Royal Information Electronics CT-1458, a multiscanning display circa 1992 which does CGA to SuperVGA (800x600) resolutions.

The "new" rig is an I7-875K running Windows 10.

More Information:
When running with a scan rate converter, you have to temper your expectations. The scan rate converter only sees a 400-line image, which will then output as two 1/60th-second fields. In other words, you can't expect 60 fps support from a scan rate converter when running low vertical resolutions emulators, 320x200 from a standard video card actually doubles up the lines and shoots out a 400 vertical line display every 1/60th of a second. You will only get 30fps max, since the scan rate converters can't possibly know that the original signal from the arcade boards was non-interlaced.

1. Emulator setup
There are no if's, and's, or but's: NVidia's drivers just work with every emulator I tested. The ATI drivers in some cases had to be finagled (for instance, 16-bit colour depths aren't supported under DirectX) or just outright refused to work, prompting me to try different emulators for the same system. MAME worked OK out of the box on both cards. ZSnes/Win was a bust on ArcadeVGA, but I was able to eventually get Snex9x working OK. I have yet to find an NES emulator that works with the special ArcadeVGA resolutions, investigation is ongoing.
Summary: ATI cards are a pain in the ass and take a lot longer to get your rig set up. The driver situation does not appear to have improved all that much from the Rage3D days, the last time I had ATI cards in my computers.

2. Image quality
Both setups produced identical image quality on all displays.

3. Scrolling display quality
Here is where things got really ugly for the GBS-8100. The ArcadeVGA produced identical results as to what I would expect, mirroring what was available by driving the LCD display directly from the video card.

The GBS-8100, however, appeared to "stutter" 2 or 3 times a second, and not just a little bit, it appeared to be repeating the same frame 4 or more times in a row. For instance, in Dragon Spirit on the Turbografx demo stage, the clouds would smooth scroll down a bit, then jump down a full cloud length. To make sure it was the GBS-8100 (and not the Geforce 740) I attached the LCD panel to the VGA-out-pass-thru connector on the GBS-8100, and the 1084 monitor to the composite video out on the GBS-8100 (both at the same time). Scrolling in several games on Magic-Engine, Kega-Fusion, SNES9x, and MAME all showed identical stuttering only on the 1084 monitor, and it was buttery smooth on the LCD display.

The GBS-8100 I purchased has no serial number, but is labelled as version 2.1, with a silkscreened date of 2015.05.28. I cannot recommend this particular scan rate converter for retrograming duties, however, it would serve fine for mostly static displays, such as upgrading an old CNC machine to use modern displays.

I hope this information is helpful to anyone else who may be considering going this route.

Edited by Shadowfire (04/16/16 10:57 PM)